In dispensing liquid medication, pharmacists will often extract liquid medication from a large bottle or vial into a reservoir syringe, such as a large 30 cc syringe, A series of small dose syringes, 3 cc for example, will be sequentially connected to the large reservoir syringe and filled from it. In the example given above, ten small dose syringes can be filled from one charge of the large reservoir syringe.
In the past there have been coupling devices for joining the small dose and reservoir syringe during this small dose syringe filling procedure. Some of these have been tubular metal couplers with a tapered female Luer sleeve at each end.
There was a problem with these previous tubular couplers because the end of the coupler used to repeatedly connect and disconnect the small dose syringe was exposed for touch contamination by the pharmacist connecting and disconnecting the series of small dose syringes. This could occur when he grasped the tubular coupler in one hand and the small dose syringe in the other to connect, or disconnect, the small dose syringe.